COMPARISON OF LIGHT-REGULATED SEED-GERMINATION IN FICUS SPP AND CECROPIA-OBTUSIFOLIA - ECOLOGICAL IMPLICATIONS

The major components of annual seed deposition in the rain forest at L os Tuxtlas, Veracruz, Mexico are seeds of the pioneer tree species Cec ropia obtusifolia and those of some species of Ficus. Cecropia obtusif olia Bertol. forms a relatively persistent viable soil seed bank, wher eas seeds of Ficus are seldom found in the soil. Both genera require l ight for seed germination; however, the species differ in their germin ation responses to far red (FR) light under laboratory and field condi tions. Seeds of C. obtusifolia did not germinate in low red/far red (R /FR) or pure FR, whereas seeds of the Ficus species did. This suggests that Ficus seeds do not become dormant under the light conditions (lo w R/FR ratio) beneath the leaf canopy of the rain forest. This differe nce may explain why the species differ in their presence in the soil s eed bank.